Commit f83ac56a authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu: Convert fpstate_init() to struct fpstate 



Convert fpstate_init() and related code to the new register storage
mechanism in preparation for dynamically sized buffers.

No functional change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.292157401@linutronix.de
parent 87d0e5be

arch/x86/kernel/fpu/core.c

+22 −22
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ 
 * Represents the initial FPU state. It's mostly (but not completely) zeroes,

 * depending on the FPU hardware format:

 */

union fpregs_state init_fpstate __ro_after_init;

struct fpstate init_fpstate __ro_after_init;



/*

 * Track whether the kernel is using the FPU state
@@ -157,7 +157,7 @@ void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask) 


void fpu_reset_from_exception_fixup(void)

{

	restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());

	restore_fpregs_from_fpstate(&init_fpstate.regs, xfeatures_mask_fpstate());

}



#if IS_ENABLED(CONFIG_KVM)
@@ -297,24 +297,24 @@ static inline unsigned int init_fpstate_copy_size(void) 
		return fpu_kernel_xstate_size;



	/* XSAVE(S) just needs the legacy and the xstate header part */

	return sizeof(init_fpstate.xsave);

	return sizeof(init_fpstate.regs.xsave);

}



static inline void fpstate_init_fxstate(struct fxregs_state *fx)

static inline void fpstate_init_fxstate(struct fpstate *fpstate)

{

	fx->cwd = 0x37f;

	fx->mxcsr = MXCSR_DEFAULT;

	fpstate->regs.fxsave.cwd = 0x37f;

	fpstate->regs.fxsave.mxcsr = MXCSR_DEFAULT;

}



/*

 * Legacy x87 fpstate state init:

 */

static inline void fpstate_init_fstate(struct fregs_state *fp)

static inline void fpstate_init_fstate(struct fpstate *fpstate)

{

	fp->cwd = 0xffff037fu;

	fp->swd = 0xffff0000u;

	fp->twd = 0xffffffffu;

	fp->fos = 0xffff0000u;

	fpstate->regs.fsave.cwd = 0xffff037fu;

	fpstate->regs.fsave.swd = 0xffff0000u;

	fpstate->regs.fsave.twd = 0xffffffffu;

	fpstate->regs.fsave.fos = 0xffff0000u;

}



/*
@@ -322,19 +322,19 @@ static inline void fpstate_init_fstate(struct fregs_state *fp) 
 * 1) Early boot to setup init_fpstate for non XSAVE systems

 * 2) fpu_init_fpstate_user() which is invoked from KVM

 */

void fpstate_init_user(union fpregs_state *state)

void fpstate_init_user(struct fpstate *fpstate)

{

	if (!cpu_feature_enabled(X86_FEATURE_FPU)) {

		fpstate_init_soft(&state->soft);

		fpstate_init_soft(&fpstate->regs.soft);

		return;

	}



	xstate_init_xcomp_bv(&state->xsave, xfeatures_mask_uabi());

	xstate_init_xcomp_bv(&fpstate->regs.xsave, xfeatures_mask_uabi());



	if (cpu_feature_enabled(X86_FEATURE_FXSR))

		fpstate_init_fxstate(&state->fxsave);

		fpstate_init_fxstate(fpstate);

	else

		fpstate_init_fstate(&state->fsave);

		fpstate_init_fstate(fpstate);

}



void fpstate_reset(struct fpu *fpu)
@@ -347,7 +347,7 @@ void fpstate_reset(struct fpu *fpu) 
void fpu_init_fpstate_user(struct fpu *fpu)

{

	fpstate_reset(fpu);

	fpstate_init_user(&fpu->fpstate->regs);

	fpstate_init_user(fpu->fpstate);

}

EXPORT_SYMBOL_GPL(fpu_init_fpstate_user);

#endif
@@ -378,7 +378,7 @@ int fpu_clone(struct task_struct *dst) 
	 */

	if (dst->flags & (PF_KTHREAD | PF_IO_WORKER)) {

		/* Clear out the minimal state */

		memcpy(&dst_fpu->state, &init_fpstate,

		memcpy(&dst_fpu->state, &init_fpstate.regs,

		       init_fpstate_copy_size());

		return 0;

	}
@@ -435,11 +435,11 @@ void fpu__drop(struct fpu *fpu) 
static inline void restore_fpregs_from_init_fpstate(u64 features_mask)

{

	if (use_xsave())

		os_xrstor(&init_fpstate.xsave, features_mask);

		os_xrstor(&init_fpstate.regs.xsave, features_mask);

	else if (use_fxsr())

		fxrstor(&init_fpstate.fxsave);

		fxrstor(&init_fpstate.regs.fxsave);

	else

		frstor(&init_fpstate.fsave);

		frstor(&init_fpstate.regs.fsave);



	pkru_write_default();

}
@@ -466,7 +466,7 @@ static void fpu_reset_fpstate(void) 
	 * user space as PKRU is eagerly written in switch_to() and

	 * flush_thread().

	 */

	memcpy(&fpu->state, &init_fpstate, init_fpstate_copy_size());

	memcpy(&fpu->state, &init_fpstate.regs, init_fpstate_copy_size());

	set_thread_flag(TIF_NEED_FPU_LOAD);

	fpregs_unlock();

}

arch/x86/kernel/fpu/internal.h

+2 −2
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
#ifndef __X86_KERNEL_FPU_INTERNAL_H

#define __X86_KERNEL_FPU_INTERNAL_H



extern union fpregs_state init_fpstate;

extern struct fpstate init_fpstate;



/* CPU feature check wrappers */

static __always_inline __pure bool use_xsave(void)
@@ -25,7 +25,7 @@ static __always_inline __pure bool use_fxsr(void) 
extern void fpu__init_prepare_fx_sw_frame(void);



/* Used in init.c */

extern void fpstate_init_user(union fpregs_state *state);

extern void fpstate_init_user(struct fpstate *fpstate);

extern void fpstate_reset(struct fpu *fpu);



#endif

arch/x86/kernel/fpu/signal.c

+1 −1
Original line number Diff line number Diff line
@@ -243,7 +243,7 @@ static int __restore_fpregs_from_user(void __user *buf, u64 xrestore, 
			ret = fxrstor_from_user_sigframe(buf);



		if (!ret && unlikely(init_bv))

			os_xrstor(&init_fpstate.xsave, init_bv);

			os_xrstor(&init_fpstate.regs.xsave, init_bv);

		return ret;

	} else if (use_fxsr()) {

		return fxrstor_from_user_sigframe(buf);

arch/x86/kernel/fpu/xstate.c

+6 −6
Original line number Diff line number Diff line
@@ -408,12 +408,12 @@ static void __init setup_init_fpu_buf(void) 
	setup_xstate_features();

	print_xstate_features();



	xstate_init_xcomp_bv(&init_fpstate.xsave, xfeatures_mask_all);

	xstate_init_xcomp_bv(&init_fpstate.regs.xsave, xfeatures_mask_all);



	/*

	 * Init all the features state with header.xfeatures being 0x0

	 */

	os_xrstor_booting(&init_fpstate.xsave);

	os_xrstor_booting(&init_fpstate.regs.xsave);



	/*

	 * All components are now in init state. Read the state back so
@@ -431,7 +431,7 @@ static void __init setup_init_fpu_buf(void) 
	 * state is all zeroes or if not to add the necessary handling

	 * here.

	 */

	fxsave(&init_fpstate.fxsave);

	fxsave(&init_fpstate.regs.fxsave);

}



static int xfeature_uncompacted_offset(int xfeature_nr)
@@ -672,11 +672,11 @@ static unsigned int __init get_xsave_size(void) 
 */

static bool __init is_supported_xstate_size(unsigned int test_xstate_size)

{

	if (test_xstate_size <= sizeof(union fpregs_state))

	if (test_xstate_size <= sizeof(init_fpstate.regs))

		return true;



	pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",

			sizeof(union fpregs_state), test_xstate_size);

			sizeof(init_fpstate.regs), test_xstate_size);

	return false;

}
@@ -981,7 +981,7 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct xregs_state *xsave, 
			       u32 pkru_val, enum xstate_copy_mode copy_mode)

{

	const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);

	struct xregs_state *xinit = &init_fpstate.xsave;

	struct xregs_state *xinit = &init_fpstate.regs.xsave;

	struct xstate_header header;

	unsigned int zerofrom;

	u64 mask;